Effects of Treatments on Some Bioactive Components of Selected Lesser Known Legumes Indigenous to Nigeria

Abstract

The effects of cooking time and roasting temperature on the total phenolics, tannin, anthocyanin, carotenoids and flavonoid contents of cowpea (Vigna unguiculata (L.) Walp), bambaranut (Vigna subterranean L.), red bean (Phaseolus vulgaris), pigeonpea (Cajanus cajan), African breadfruit (Treculia africana), African yam bean (Sphenostylis stenocarpa) seed, African oil bean (Pentaclethra mycrophylla Benth.) and groundnut (Arachia hypogea) were evaluated. The results revealed that pressure cooking times exhibited significant (p<0.05) reduction in the total phenolic, tannin, anthocyanin, carotenoid and flavonoid contents of all the samples with increasing cooking time. However, there was minimal increase in the total phenolic and carotenoid contents of red bean; total anthocyanin of red bean and African oil bean. Dry heat (roasting) temperatures significantly (p<0.05) reduced the phenolic content of the samples except in bambaranut, red bean and African oil bean where there were increases with increasing roasting temperature. The tannin, anthocyanin, carotenoid and flavonoid contents were significantly (p<0.05) reduced with increasing roasting temperatures. Therefore, for increase phenolic content in bambaranut, red bean and African oil bean cooking for 40 min and 50 min and roasting bambaranut, African oil bean and groundnut at 140o C should be adopted.